You Do Need power plug adapter while traveling from Saint Barthélemy to Sint Maarten.

Here is Why You Need An Adapter

The outlet and plug type used in Sint Maarten are A and B and in Saint Barthélemy are C and E. This is how they look like.

Saint Barthélemy

In Saint Barthélemy, outlets of type C and E are in use.

Type C

Type E

Sint Maarten

In Sint Maarten, outlets of type A and B are in use.

Type A

Type B